In AKI, dying renal cells release intracellular molecules that stimulate immune cells to secrete proinflammatory cytokines, which trigger leukocyte recruitment and renal inflammation. Whether the release of histones, specifically, from dying cells contributes to the inflammation of AKI is unknown. In this study, we found that dying tubular epithelial cells released histones into the extracellular space, which directly interacted with Toll-like receptor (TLR)-2 (TLR2) and TLR4 to induce MyD88, NF-kB, and mitogen activated protein kinase signaling. Extracellular histones also had directly toxic effects on renal endothelial cells and tubular epithelial cells in vitro. In addition, direct injection of histones into the renal arteries of mice demonstrated that histones induce leukocyte recruitment, microvascular vascular leakage, renal inflammation, and structural features of AKI in a TLR2/TLR4-dependent manner. Antihistone IgG, which neutralizes the immunostimulatory effects of histones, suppressed intrarenal inflammation, neutrophil infiltration, and tubular cell necrosis and improved excretory renal function. In summary, the release of histones from dying cells aggravates AKI via both its direct toxicity to renal cells and its proinflammatory effects. Because the induction of proinflammatory cytokines in dendritic cells requires TLR2 and TLR4, these results support the concept that renal damage triggers an innate immune response, which contributes to the pathogenesis of AKI.

Aims/hypothesis Chemokine (C-X-C motif) ligand 12 (CXCL12) (also known as stromal cell-derived factor-1 [SDF-1]-alpha) is a homeostatic chemokine with multiple roles in cell homing, tumour metastasis, angiogenesis and tissue regeneration after acute injuries. However, its role in chronic diseases remains poorly defined, e.g. in chronic glomerular diseases like diabetic glomerulosclerosis. We hypothesised that CXCL12 may have a functional role during the evolution of diabetic glomerulosclerosis, either by assisting glomerular repair or by supporting the maladaptive tissue remodelling in response to hyperglycaemia and glomerular hyperfiltration. Methods To define the functional role of CXCL12 in the progression of glomerular disease, we used the CXCL12-specific inhibitor NOX-A12, an L-enantiomeric RNA oligonucleotide (Spiegelmer). A mouse model of type 2 diabetes (db/db mice) was used. Male db/db mice, uninephrectomised at 6 weeks of age, received subcutaneous injections with a PEGylated form of NOX-A12, nonfunctional control Spiegelmer or vehicle on alternate days from 4 to 6 months of age. Results Immunostaining localised renal CXCL12 production to glomerular podocytes in db/db mice with early or advanced diabetic nephropathy. CXCL12 inhibition significantly reduced the degree of glomerulosclerosis, increased the number of podocytes, prevented the onset of albuminuria and maintained the peritubular vasculature without affecting blood glucose levels, body weight or glomerular macrophage infiltration. Conclusions/interpretation We conclude that podocytes produce CXCL12, which contributes to proteinuria and glomerulosclerosis in our mouse model of type 2 diabetes. This novel pathomechanism provides the first evidence S. G. Sayyed and H. Hägele contributed equally to this study. Electronic supplementary material The online version of this article

Complexed dsRNA enters GEnC via clathrin endocytosis and activates GEnC via RIG-1 in the cytosol to produce inflammatory cytokines, chemokines and type I interferons. Furthermore, RNA induces ICAM-1 expression and increases GEnC permeability. All of these mechanisms may contribute to the onset or aggravation of glomerulonephritis associated with RNA virus infections.

Viral DNA induces potent antiviral immunity by activating dendritic cells; however, the mechanism governing viral DNA-mediated triggering or aggravation of glomerulonephritis is unknown. Glomerular endothelial cells (GEnCs) do not express toll-like receptor (TLR)9, the only DNA-specific TLR. We therefore hypothesized that DNA could activate GEnCs via the recently discovered TLR-independent viral DNA recognition pathway. Indeed, double-stranded non-CpG (B-) DNA activated GEnCs to produce interleukin-6, CCL5/RANTES, CCL2/ MCP-1, CXCL10/IP10, interferon (IFN)-␣, and IFN-␤ when cationic lipids facilitated intracellular DNA uptake. This cytokine production was inhibited by chlorpromazine , suggesting that clathrin-dependent endocytosis is required for B-DNA entry. However , chloroquine and MyD88 inhibition did not affect GEnC activation, suggesting TLR-independent DNA recognition. In addition, IFN-␤ activated cytokine and chemokine mRNA expression, although only CXCL10/IP10 was induced at the protein level, and type I IFN did not activate GEnC in an autocrine-paracrine auto-activation loop. B-DNA complexes induced intercellular adhesion molecule-1 expression at the GEnC surface and increased intercellular adhesion molecule-1-dependent leukocyte adhesion and microvascular extravasation in vivo. Furthermore, B-DNA complexes increased albumin permeability of GEnC monolayers in culture or microvascular dextran leakage in vivo. In addition, B-DNA complexes impaired GEnC proliferation. Thus, complexed B-DNA activates GEnC to produce cytokines, chemokines , and type I IFNs , increases leukocyte adhesion and microvascular permeability , and reduces GEnC proliferation via a MyD88-independent cytosolic DNA recognition pathway. This innate antiviral response program suggests a novel pathomechanism regulating DNA virus-mediated induction or aggravation of glomerulonephritis.

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Background:The anti-von Willebrand factor (VWF) nanobody caplacizumab directly prevents the fatal microthrombi formation in immune-mediated thrombotic thrombocytopenic purpura (iTTP), thereby adding a new therapeutic principle to the treatment of this disorder. However, real-world treatment modalities beyond clinical trials remain heterogeneous.Methods: Here, we describe the risks and benefits of an alternate-day dosing regimen for caplacizumab by thoroughly analyzing the timing and outcome of this approach in a retrospective cohort of 25 iTTP patients treated with caplacizumab at seven different medical centers in Austria and Germany between 2018 and 2021.Results: Alternate-day dosing of caplacizumab appeared feasible and led to persisting normal platelet counts in most patients. Five patients experienced iTTP exacerbations or relapses that led to the resumption of daily caplacizumab application. VWF activityThis is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

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